Since 1988, the ancient arena in Nîmes, which was previously used only in the summer months, has been a stage for winter events, too. This was made possible by the installation of a removable roof structure over the 5,000 m² area. Functional and conservational constraints determined the form of the design to a large extent. The roof was not to be visible from the outside; and no changes could be made to the classical structure of the arena. In addition, the client required as great an intensity of light in the interior as possible, as well as facilities for heating the space.